This invention relates generally to plastic pipe fittings and in particular to a new and novel design for a plastic pipe fitting for use in underground water sprinkling systems where the fitting is attached to sprinkler heads of different sizes.
In the layout of underground water sprinkling systems it is common to use different sizes of pop-up sprinkler heads, depending upon the area needed for water coverage. Smaller 1/2 inch sprinkler heads are usually used for the small areas up to a 15 foot throw and usually contain stationary heads with set spray patterns. These smaller sprays can distribute approximately 0.9 gallons per minute of water up to 3 gallons per minute and are manufactured by Toro Corp., Rainbird Manufacturing Company and Hunter Heads Company, among others.
Larger 3/4 inch sprinkler heads are usually used for larger areas and generally have oscillating heads that can spray water to a distance of 41 feet to 60 feet and are also capable of 360.degree. rotation. The larger sprinkler heads can distribute approximately 3 gallons per minute of water up to 6 gallons per minute and are manufactured by the same companies that manufacture the smaller heads.
Since it is common to have some layouts which require all small sprinkler heads and other layouts which may require all large heads or a mixture of both, the installer of the sprinkling system needs to have a supply of both sizes of sprinkler heads as well as attaching pipe fittings. In addition the distributor must also stock these dual sizes of sprinkler heads and fittings for the purchasing public, which results in large stocks of inventory to both. It would be advantageous to be able to manufacture, distribute and use only one attaching pipe fitting which could be used with both the large as well as small sprinkler heads.
It would also be advantageous to have several types of attaching pipe fittings which are capable of being used to replace a variety of fitting connections to thereby reduce installation time and cost of the entire system.
The normal pipe fittings that are used to attach to the various sizes of sprinkler heads are generally sized for a 1/2 inch or 3/4 inch outlet, according to the size of sprinkler head used and all contain nominal 1 inch O.D. connecting barbed inlets. Plastic pipe is then positioned over the barbed inlets and held tightly on the barbs by a stainless steel clamp or other means. Since the prior art type attaching pipe fittings are manufactured with a large space between the last barb and the central body of the fitting, it is not uncommon to accidentally clamp the plastic pipe in the non-barbed area. When this occurs, the fitting will usually blow apart when water pressure is applied since the prior art type fittings are designed to be clamped over the barbed area. It would be desirable to have a pipe fitting that would be foolproof in that the installer would not be able to accidentally clamp the pipe fitting in the wrong area.
A prior art pre-examination patent search of dual type fittings was conducted in class 285, subclasses 175, 177 and 390. The U.S. Pat. No. #432,248 issued to G.O. Rinman teaches the use of multiple internal threads on a coupling nut to engage different size pipe threads at the same time for two pipes.
The U.S. Pat. No. #4,688,832 issued to Donald J. Ortloff teaches the use of double internal threads in oil drill pipe to provide a means for prestressing the joint to uniformly distribute the forces throughout the coupling joint. A similar type of design is taught in the U.S. Pat. No. #4,796,928 issued to Frank J. Carlin et al and uses a particular configuration on a two-step internal thread to eliminate variations in tensile strength caused by wall thickness variations.
Multiple straight female internal bores of different sizes are taught in the U.S. Pat. No. #4,774,940 issued to Gerald S. Linder in connection with a medical breathing circuit connector. The internal bores have slightly different diameters of approximately 0.1 millimeters to enable the unit to seat on the mating input section thereby reducing the internal forces that cause the coupling to disconnect.
A multiple sized male connection for attaching to a vehicle exhaust pipe is taught in the U.S. Pat. No. #4,779,904 issued to Christopher K. Rich. The connection is externally ribbed to assist in retaining different diameters of exhaust conduit.
The U.S. Pat. No. #4,266,813 issued to Robert D. Oliver teaches a universal coupler for use on a recreational vehicle to permit different type bottles of liquids, such as chlorine, antifreeze or the like, to be added to a water system for cleanout purposes. A plurality of different sizes and types of female threads are used in the design.